### What this PR does / why we need it? bugfix short squence has no respone. This pull request refactors the event handling for KV cache reshaping in mla_v1.py by centralizing the reshape_cache_event creation and recording within the _mla_preprocess function, ensuring it covers both decode and prefill operations. Signed-off-by: wangxiaoteng <wangxiaoteng@huawei.com>